Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 29: Poster Session: Spintronics; Spin-controled transport; Topological insulators; Interfaces / Surfaces; Magnetic semiconductors
HL 29.5: Poster
Montag, 11. März 2013, 16:00–20:00, Poster A
Anomalous spin diffusion in high-mobility (110) GaAs-based quantum wells — •Markus Schwemmer1, Roland Voelkl1, Tobias Korn1, Michael Griesbeck1, Sergey Tarasenko2, Dieter Schuh1, Werner Wegscheider3, and Christian Schueller1 — 1Institute of Experimental and Applied Physics Faculty of Physics, University of Regensburg, Germany — 2A. F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia — 3ETH Zurich, Switzerland
We have performed spin diffusion measurements in high-mobility two-dimensional electron systems embedded in a symmetrical GaAs/AlGaAs quantum well grown in [110] direction. For mapping the diffusion of spin-polarized electrons in the sample and to determine the corresponding spin lifetimes, we use a two-beam Hanle-MOKE method. The spin diffusion was studied by moving the pump beam with respect to the probe beam using a motorized mirror. With this technique we could observe diffusion lengths as high as 50 µm for low temperatures. The diffusion length was constant over a wide temperature range (4 - 40 K). Due to a reduced influence of the photogenerated holes, a maximum of the net spin polarization is observed at a distance of a few µm away from the pump spot. Additionally, we manipulated the resident electron density by above-barrier-illumination and investigated its effect on the diffusion length. Financial support by the DFG via SFB 689 and SPP 1285 is gratefully acknowledged.